Generally a key for a cylinder lock comprises an elongated shaft that has a combination portion operative to engage one or more pin mechanisms within a plug of the cylinder. The pin mechanisms in the lock typically serve to obstruct rotation of the plug when locked. The combination portion on the shaft includes varying cuts and/or indentations, in a unique combination that matches corresponding pins in the matching cylinder lock. When a matching key is inserted inside a keyway of a plug of the cylinder lock, a shear line of the plug is freed so that the key may be turned to lock or unlock the cylinder lock. By providing different combinations of key features, key manufacturers are capable of supplying many different locks and matching keys that are uniquely associated and therefore not interchangeable, thus preventing opening a lock with a key that is not originally designed for the same lock. More recently, the option of adding resilient protrusions with pre-defined heights to the combination portion of keys and corresponding pins to the cylinder lock has been provided.
Israel Patent Publication No. IL137053 entitled “Locking System” assigned to Asher Haviv, the contents of which is incorporated herein by reference, describes a key blank including a first and second push-pin positioned on opposite surfaces of a key shaft and equally offset from a centerline of the combination surface. The push pins are under pressure from within the key shaft to extend outwardly from their respective surfaces. The push-pins can be pushed into a keyway of a lock with applied force and are operable to displace at least one lock pin that extends into a rotatable plug of the lock and to release the shear line of the plug so that the plug can be rotated. When the key is inserted into the lock, the push-pins are pushed into the key so that the key can pass into the keyway.
U.S. Patent Publication No. 2008/0236223 entitled “Key Combination element in Key Blank and Key”, the contents of which is incorporated herein by reference, describes a resilient element disposed through a bore in a shaft of a key blank so that it protrudes from both surfaces of the shaft. In operation, when inserted into a keyway of a lock, one protruding end of the element applies an urging force to unlock a lock combination element in response to the other end being pushed inward by a wall in the keyway.
U.S. Pat. No. 5,839,308 entitled “Locking Apparatus”, the contents of which is incorporated herein by reference, describes a key blank including a movable pin element retained within a shaft of the key blank. The movable pin element is operable to be displaceable in a single direction, outwardly from the key combination surface. When inserted into a corresponding lock, a spring loaded pin housed within a plug of the lock urges the movable pin element on the key shaft into operative engagement with a another a pin assembly on an opposite side of the shaft so that shear line of the plug is released and the plug is allowed to rotate.
International Patent Application Publication No. WO/0057006 entitled “Key blank and resiliently protruding pins”, the contents of which is incorporated herein by reference, describes a key blank with at least one resiliently protruding pin element on a shaft of the key that partially protrudes from a surface of the shaft while no external forces are applied on the protruding pin and retracts inwardly into a cavity in response to an external force exerted on it. In operation, the resiliently protruding pin actuates an internal mechanism provided within a lock.
United Kingdom Patent Application No. 2,161,204 entitled “A key for a lock”, the contents of which is incorporated herein by reference, describes a pair of aligned moving bodies positioned in opposite edges of a shaft of a key. A dedicated spring acts on each of the moving bodies to cause a head of the body to protrude beyond the shaft. The key is used with a lock provided with locking pins that are driven by the moving bodies into an unlock position.